1. Field of Invention
The present invention relates generally to power supplies and more particularly to air ventilation cooling systems for a portable power device.
2. Description of Related Art
Portable power devices, such as power converters and fuel cells, can become very hot when used for an extended period of time. In a portable power device, which is typically rectangular, heat is transferred through all side surfaces of the device except for the largest bottom surface. The bottom surface in a conventional portable power device is an ineffective surface for the purpose of heat dissipation.
One conventional solution provides a portable power device with an external enclosure in which a number of open air vents exist on the top and bottom covers. Another conventional solution provides an external enclosure that supports an inner thermally conductive enclosure with a gap between them to facilitate ventilation. These ventilation constructions, however, possess several disadvantages. First, liquid may enter into a sealed enclosure through openings on the top of the enclosure. Second, the temperature rise inside of an enclosure needs to create sufficient pressure difference to generate air movement. Third, spaces that are utilized for air passages may reduce the overall package usable volume as well as increase the thermal resistance to ambient.
Accordingly, there is a need for an air ventilation cooling structure for a portable power device that produces a more efficient heat dissipation effect.